MODFLOW-2000 model used to evaluate alternative withdrawal strategies on groundwater flow in the unconfined Kirkwood-Cohansey aquifer system, the Rio Grande water-bearing zone, and the Atlantic City 800-foot sand in the Great Egg Harbor and Mullica River Basins, New Jersey
Description
A three-dimensional groundwater-flow model (MODFLOW-2000 ) of the
Kirkwood-Cohansey aquifer system, Rio Grande water-bearing zone,
and Atlantic City 800-foot sand in the Great Egg Harbor and Mullica
River Basins, N.J. was developed to simulate the effects of withdrawals
on streamflow and groundwater supply. Increasing groundwater
withdrawals from the unconfined Kirkwood Cohansey aquifer system is
a major concern because of the potential for streamflow depletion and
the resulting ecological effects on aquatic habitats, wetlands, and vernal
ponds. In the confined Atlantic City 800-foot sand aquifer water levels
have been steadily declining and most of the groundwater withdrawn
from the Atlantic City 800-foot sand ultimately comes from the Kirkwood
-Cohansey aquifer system. The groundwater flow model was used to
simulate scenarios under three possible conditions: average 1998 to
2006 withdrawals (Average scenario), full-allocation withdrawals (Full
Allocation scenario), and projected 2050-demand withdrawals (2050
Demand scenario). Three adjusted scenarios, variations of the Average,
Full Allocation, and 2050 Demand scenarios, were simulated where
withdrawals were modified in stages with the intent to successively
eliminate or minimize the base-flow deficits. Monthly base-flow depletion
criteria were determined using the NJDEP Low-Flow Margin method to
estimate available water on an annual basis and if water-supply deficits
exist. The model simulates monthly stress periods from 1998 through
2006. An existing regional model of the New Jersey Coastal Plain was
revised to provide boundary conditions for the Great Egg Harbor and
Mullica River Basin model (GEM). This USGS data release contains all
of the input and output files for the simulations described in the associated
model documentation report (http://pubs.usgs.gov/sir/2012/5187/).